Bus operations as precursors of light rail transit

Seattle — Link LRT trains (left) and BRT buses share the Downtown Seattle Transit Tunnel, originally installed as a busway.

Seattle — Link LRT trains (left) and BRT buses share the Downtown Seattle Transit Tunnel, originally installed as a busway.


by Lyndon Henry

High-quality bus services – often characterized as “Bus Rapid Transit” (BRT) – are frequently portrayed as possible precursors of electric light rail transit (LRT) systems. But can BRT or “BRT-like” bus operations effectively fulfill such a role?

This question was examined in a paper that I and my colleague Dave Dobbs (executive director of the Texas Association for Public Transportation, and publisher of the Light Rail Now website) presented to the Joint International Light Rail Conference co-sponsored by the U.S. Transportation Research Board and the American Public Transportation Association in April 2009 in Los Angeles.

The formal paper, Bus Rapid Transit as a Precursor of Light Rail Transit? is available online, starting at p. 137 of the full conference proceedings:

http://onlinepubs.trb.org/onlinepubs/circulars/ec145.pdf

Our study includes general research as well as an examination of several specific case studies, drawn from both actual operations and planned operations. Our analysis identifies factors that may optimize the capability of of these kinds of bus operations to function more effectively as precursors of LRT systems, but emphasizes that “initial system design, to permit a transition, is critical, and major challenges and drawbacks must be addressed and overcome.”

Our conclusions spell out some details:

This analysis has identified certain factors that may optimize the capability of Bus Rapid Transit to function effectively as a precursor of a light rail transit system. However, it is important for planners to keep in mind that initial system design, to permit a transition, is critical, and major challenges and drawbacks must be addressed and overcome. A major consideration is that the BRT facilities should not represent an obstacle to the subsequent LRT project. As noted, BRT-specific infrastructure (including stations) should ideally be designed to be very low in cost so the sunk cost for BRT is not an impediment to eventual conversion to LRT.

The examples of actual or prospective BRT-to-LRT conversion in both Seattle and Ottawa (and in fact Guadalajara as well) involve some degree of transit service shutdown or disruption on the BRT facility during the conversion process in these types of “high-end”, exclusive facilities. In contrast, a “lower-end” express-bus type of BRT service can probably more readily continue a parallel service on adjacent highway or arterial lanes (if they are available) during the conversion period – although generally without stations and intermediate interchange of transferring passengers (an essential characteristic of LRT which planners should seek in BRT if the BRT service is intended to offer really the same kind of service as LRT).

In addition, the staging and logistics of conversion must be considered, particularly to avoid or minimize disruption of the existing BRT-type service while the LRT installation project is under way. In this regard, alignments in or alongside existing arterials provide at least some opportunity for maintaining a parallel BRT or bus-substitute service; on the other hand, alignments that have appropriated railway ROW for BRT (such as the Ottawa Transitway) make it virtually impossible to maintain a true parallel bus service – thus representing a serious obstacle facing conversion to LRT.

On the whole, the case studies cited suggest that actual experience is still inconclusive as to full cost-effectiveness of some forms of BRT service functioning as precursors to LRT and other type of rail transit. However, several examples approaching implementation in the near future appear to show show promise. As these planned BRT-to-LRT conversions become operational, an updated assessment should be carried out.

For additional information, plus useful graphics, check out the PowerPoint presentation shown at the conference:

Bus Rapid Transit as a Precursor of Light Rail Transit?